Dry hair and scalp should be treated with products that contain moisturizers and:

The treatment for dry hair and scalp should focus on replenishing moisture and providing nourishment. Emollients are the correct choice as they are substances that help to soften and soothe the skin or hair. They create a barrier on the surface that prevents water loss, effectively hydrating and improving the overall texture of dry hair and scalp.

In contrast, surfactants are generally used for cleaning and may not offer any moisturizing benefits; they can even be too harsh for dry conditions. Proteins can provide structure and strength to the hair but are typically more suitable for strengthening rather than moisturizing. Dyes primarily serve aesthetic purposes and do not contribute to improving moisture levels. Therefore, emollients are essential in the formulation of products designed to tackle dryness, making this choice the most appropriate for treating these conditions.